问题

某次启动canal之后，instance始终不能处理binlog，查看日志发现如下报错

2021-01-11 23:32:06.987 [destination = jdp , address = /127.0.0.1:3306 , EventParser] ERROR c.a.o.canal.parse.inbound.mysql.dbsync.DirectLogFetcher - I/O error while reading from client socket
java.io.IOException: Received error packet: errno = 1236, sqlstate = HY000 errmsg = Could not find first log file name in binary log index file
	at com.alibaba.otter.canal.parse.inbound.mysql.dbsync.DirectLogFetcher.fetch(DirectLogFetcher.java:102) ~[canal.parse-1.1.4.jar:na]
	at com.alibaba.otter.canal.parse.inbound.mysql.MysqlConnection.dump(MysqlConnection.java:235) [canal.parse-1.1.4.jar:na]
	at com.alibaba.otter.canal.parse.inbound.AbstractEventParser$3.run(AbstractEventParser.java:265) [canal.parse-1.1.4.jar:na]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_252]
2021-01-11 23:32:06.988 [destination = jdp , address = /127.0.0.1:3306 , EventParser] ERROR c.a.o.c.p.inbound.mysql.rds.RdsBinlogEventParserProxy - dump address /127.0.0.1:3306 has an error, retrying. caused by 
java.io.IOException: Received error packet: errno = 1236, sqlstate = HY000 errmsg = Could not find first log file name in binary log index file
	at com.alibaba.otter.canal.parse.inbound.mysql.dbsync.DirectLogFetcher.fetch(DirectLogFetcher.java:102) ~[canal.parse-1.1.4.jar:na]
	at com.alibaba.otter.canal.parse.inbound.mysql.MysqlConnection.dump(MysqlConnection.java:235) ~[canal.parse-1.1.4.jar:na]
	at com.alibaba.otter.canal.parse.inbound.AbstractEventParser$3.run(AbstractEventParser.java:265) ~[canal.parse-1.1.4.jar:na]
	at java.lang.Thread.run(Thread.java:748) [na:1.8.0_252]
2021-01-11 23:32:06.988 [destination = jdp , address = /127.0.0.1:3306 , EventParser] ERROR com.alibaba.otter.canal.common.alarm.LogAlarmHandler - destination:jdp[java.io.IOException: Received error packet: errno = 1236, sqlstate = HY000 errmsg = Could not find first log file name in binary log index file
	at com.alibaba.otter.canal.parse.inbound.mysql.dbsync.DirectLogFetcher.fetch(DirectLogFetcher.java:102)
	at com.alibaba.otter.canal.parse.inbound.mysql.MysqlConnection.dump(MysqlConnection.java:235)
	at com.alibaba.otter.canal.parse.inbound.AbstractEventParser$3.run(AbstractEventParser.java:265)
	at java.lang.Thread.run(Thread.java:748)
]

分析原因

从日志中Could not find first log file name in binary log index file可以看出是起始位点错了，重新制定起始的位点就可以了。我这里是因为我长时间没有运行，binlog的日志文件被删除了，导致找不到起始位置

解决

我是去了canal安装目录下的配置文件目录中，找到对应的instance名字，进入配置中删除掉meta文件。这个文件打开看下可以发现里面记录了上一次binlog的位置信息，我直接把他删了的话canal再次启动会读取最新的，如果想指定位置也可以直接配置

有的小伙伴说他删了meta文件，但是依然有报错，我这里总结一下我遇到这种现象的时的情况：

1. 删除meta文件的时候，canal还在运行，当canal关闭的时候会再次生成。对于这种情况要先停掉服务，然后再删除文件；
2. 在canal admin的instance对应配置中配置了binlog的position信息，那么在没有meta文件的情况下他会使用canal admin中配置的信息。这种情况下吧canal admin中的配置去掉或者设置成自己想要的位置信息就可以了；